Automatic train control system for railroads



May 14, 1940. 2,201,116

AUTOMATIC TRAIN CONTROL SYSTEM FOR RAILROADS I P, w. SMITH Filed Jan. 28, 1939 llllllllllllllllllly 1N ENTOR. W

ATTORNEY:

ment by the engineer.

Patented May 14, 1940 UNITED STATES PATENT orFicE AUTOMATIC TRAIN CONTROL SYSTEM FOR RAILROADS Percy W. Smith, New York, N. Y., assignor to General Railway Signal Company, Rochester, N. Y.

Application January 28, 1939, Serial No. 253,363

7 Claims.

change to more restrictive traffic conditions.

In certain train control systems, such for example, as in the Hailes patent, Re. 19,599, dated June 4, 1935, a whistle valve is provided which becomes deenergized, and sounds, upon conditions changing to more restrictive, and to silence the whistle, a manual act, known as acknowledgmerit, must be performed. If the whistle should fail to sound, due to a failure of air pressure, for example, a dangerous condition might exist which would not be properly brought to the attention of the engineer, and accordingly, to provide against any such contingency, the present invention provides an automatic means for insuring against such a failure of the whistle valve.

More specifically, according to the present invention, a system is provided wherein, upon a change in trafiic conditions to more restrictive conditions, a whistle becomes deenergized and sounds and can be silenced only by acknowledg- The whistle is operated by air pressure from any convenient source such as the main reservoir, and should the pressure in the main reservoir fail or should it be carelessly cut off from the whistle, a check device operates to put the cab signal to stop, whereby to insure that the engineer shall not be unsafely misled as to the traffic conditions in advance.

In the drawing are shown, in a wholly schematic manner, and in no way whatsoever in a limiting sense, two forms which the present invention can assume. In the drawing:

Fig. 1 is a diagrammatic view of one form of the invention.

Fig. 2 is a fragmentary view of a modified form of the invention.

Referring now to the drawing, and first to Fig.

1, there is here shown a stretch of track, constituted by track rails I, separated into isolated blocks by insulating joints 2. Across the rails at one end of each block, is connected a track relay TR while a track battery TB is connected across the other end of each block, in series with an adjustable inductance 3 an adjustable resistance 4 and the secondary 5 of a transformer 6 the primary 1 of which is connected across a source of alternating current of some non-commercial frequency such as 100 cycles per second,

with the energy controlled by contact finger 8 and front point of the track relay for the block next in advance, a contact finger 9 and front point, of a coding motor (3M and a contact finger I0 and front point of an approach control line relay H2. The line relay H is energized upon the release of the track relay at the entrance end of the block in question. For example, line relay H 'picks up upon the release of track relay TR whereby to energize the code motor CM and place coded current on the exit end of the block just entered, provided the block next in advance is not then occupied.

The code motor CM can be of any usual or desired type, such as disclosed in the Hailes patent above referred to, and can interrupt the train control alternating current at a suitable rate, as for example, 180 times per minute.

Furthermore, it should be understood that a very simple type of trackway apparatus and circuits has been disclosed, in order to exemplify the present invention, and that a more complex system having a plurality of different codes, and accordingly, a largernumber of cab indications, could equally well be employed, and is contemplated by the present invention.

With the trackway apparatus as above disclosed, it is clear that upon a train entering a block, code is placed on the exit end ofs'uch block, having a rate, for example,.of 180 per minute, provided the block next in advance is not then occupied. If the block next in advance is occupied, the track transformer is held deenergized, and no control current is placed on the track rails of the block just entered.

Referring now to the car carried apparatus, a car, or locomotive, is indicated by the wheels and axle l3, as occupying the block C, traffic being assumed in the direction of the arrow l2, while another car M is indicated as occupying the block A. Carried in front of the first pair of wheels and axle, are receiving devices l5, constituted by two windings connected in series so that the voltages, induced therein by train control alternating current flowing in the track rails, are cumulative.

The receivers are connected to the primary of a transformer MTR, through a circuit including condensers ltand ll for tuning the circuit substantially to resonance, at 100 cycles per second. The secondary of transformer MTR controls the grid i8 of tube Tl, the plate circuit of which includes the primary of transformer TRi, the secondary of which controls ,the voltage of the grid I9 of a second tube T2. The plate circuit of tube T2 includes the primary of transformer TR2, the secondary ofwhich controls the input to rectifier R3 of the double wave type, with the output of the rectifier connected across a coding relay CR.

2| of a transformer TR3, thus constituting what is conveniently termed a push-pu1l transformer arrangement, of the same general type as disclosed in the Hailes patent.

The secondary of transformer TR3 is connected, through a tuning condenser 22, to the input side of a double wave rectifier R6, the output of which controls the energization of a relay IBGR. Relay iBBR is made somewhat slow acting, both on pick up and release, as by means of proper slugs or the like, and a magnetic bridge, or the like, as for example, in the Field Patent 1,824,130, granted September 22, 1931, for a purpose to be described below.

From the above described circuits it can be seen that relay 180R picks up on receiving energy coded at the proper rate, and stays up so long as energy is being received, it holding up during the current off periods of the code, due to its slow acting characteristics.

The system includes a cab signal of any desired type, the one shown to exemplify the present invention being a very simple type involving a signal G, or clear signal, and indicating proceed, and a signal R, or stop signal, and indicating stop, with these signals controlled respectively by the front and back points of contact finger 23 of relay IBDR.

The acknowledging circuits are so arranged as to require acknowledgement by the engineer upon a change to more restrictive conditions, and includes an acknowledging relay AR, and an acknowledging contactor AckC, which is biased, as by a spring 24, to assume the position shown.

The warning, or penalty, device, 1. 'e.-whist1e valve WV, employed in this invention, comprises a casing 25, having a whistle 26 which sounds upon air under pressure passing out through the orifice 27, which orifice connects with a passage 28 controlled by a valve 29 which has operating coils 30 which, when energized, overcome the bias of a spring 31 and causes the valve 28 to be seated on its seat 32, and hence, maintain the whistle silent. Upon spring 31 moving valve ,29 upwardly, the whistle is put into communication with a passage 33 connected to a pipe 34 which, by way of a valve 35, communicates with any suitable source of air under pressure, such as the main reservoir MR. The pipe 34 also connects to a pneumatically controlled device CD, which includes an air tight chamber 36, having a flexible diaphragm 31, which is connected, by means of a stem 38, to a contact member 39, which, when moved upwardly by a biasing means, such as a spring 40, interconnects the two wires 4! and 42, to complete a shunt across the receivers I5, and shunt out the signal control cirsuits and devices carried on the car.

Considering now the car M, which is in a block which is receiving coded energy, this coded energy picks up relay IBUR to thereby energize the G, or clear, signal, through contact finger 23 and front point, whereby to appraise the engineer that traffic conditions are safe and that he should proceed at speed.

. Assume now that car l3 remains where it is, in block C, while car It advances eastwardly and enters block 13. In this block, there is no train control energy in the track rails, due to track relay TR having released its contact finger 8?. As a result, relay lSllR releases to thereby change the cab signal from G to R, or stop. The whistle valve WV, which has been energized through a circuit including contact finger S2 and front point of relay iEBR, contact finger Q3 and back point of acknowledging relay AR, contactor 4 3 and front point of the acknowledging contactor AclcC, and wire 45, becomes deenergized upon the release of code relay iBllR, whereupon valve 29 opens and whistle 28 sounds.

In order that the whistle be silenced, the engineer must depress the acknowledging contactor AclcC, whereby to close the reverse contactor 46 on its back point, to thereby pick up acknowledging relay AR, through a circuit including contact finger 4'5 and front contact, normal contactor 44, wire Q5, and the windings 35) of WV, whereby to close valve 29 and silence the whistle.

It should be noted that the air pressure in pipe 34 is acting on the upper face of the diaphragm 3'! of control device CD, to hold contactor 39 in depressed position, whereby to maintain the shunt circuit across the receivers iii in an open condition.

If we now assume that car it advances so as to leave block C, while car M is occupyng block B, code at the i863 rate is then received-whereupon relay 180R picks up to put the cab signal to G, or clear, and to cause the release of relay AR and reenergize the whistle valve WV through the circuit first traced therefor, that is, contact finger 42 and front point, etc.

The whistle valve WV, it will be noted, becomes deenergized only momentarily upon this change to more favorable trafiic conditions, it being deenergized while contact finger 42 moves from its back point to its front point. If the whistle be quick acting it may give a very short blast and then become silent, or, if it be slow acting, this momentary deenergization will not cause any sound to be emitted; and it is contemplated that the whistle can be made either fast. or slow acting, as desired. 1

The slow acting characteristics of the code relay ESBR are incorporated into this relay in order that a mere temporary or incidental change in the energy being received by the car, shall not immediately change the signals and cause confusion.v For example, at crossovers and the like,

relay ISBR is made slow enough to release to bridge over these temporary absences of train control energy. Also, after running in danger territory, the slow pick up characteristics of the is safeguarded by appraising the engineer upon every change to less favorable traffic conditions, by means of a whistle blast which persists until acknowledged. If the air pressure should fail, the pipes became clogged, or should valve 35 be inadvertently left closed, the whistle might fail to sound ,when it should sound, and thus produce a dangerous condition. To provide against this, the control device CD is employed, whereby, upon any such failure of air pressure, spring 40 closes contactor 39 on its front points to thereby complete a shunt circuit across the receivers, so as to shunt out the receiving apparatus and produce a stop condition on the locomotive, including a cab stop signal R. In this manner, even though the train be traveling in clear territory, a failure of air pressure will produce a stop signal, and thus safeguard against possible accidents.

Furthermore, when the car is taken out of service, the valve 35 can be turned. to close pressure oii the pipe 34, as otherwise the whistle would sound continuously since no code is being received by the car when out of service, and the sources of energy employed on the car would ordinarily be disconnected.

Upon cutting the car into service, even though it should be operating in clear territory, the signal will be R, or stop, due to the control device CD having completed the shunt across the car carrying receivers, unless air pressure has been conducted to the whistle WV and the control device CD by means of opening valve 35. Thus, the engineer is checked against failure to remember to place air pressure on the system, and thus it is assured that the engine cannot operate under proceed conditions unless it is safeguarded by having air pressure placed on the protective apparatus of this system.

In the modified form of invention of Fig. 2, the receiving circuit from the receivers I5, is carried through the diaphragm operated contact 39 and is closed, so long as there is no failure of air pressure. Upon failure of air pressure, this circuit is opened, and the cab signal is put at stop, as in the first form described.

The above rather specific description of one form which this invention can assume, has been given solely by way of example and is not intended in any manner whatsoever in a limiting sense. It should be understood that the present application contemplates all such modifications and variations as may prove desirable or useful in the circuit, insofar as they are not specifically excluded by a reasonable interpretation of the appended claims.

Having described my invention, I now claim:

1. In a train control system, in combination with trackway apparatus for putting train control current on the track rails in accordance with trafiic conditions ahead; car carried apparatus including, a receiver, a cab signal having a plurality of aspects of varying restrictivenesses, circuit means controlled by the receiver and controlling the signal, a normally inactive penalty warning device, means for making the penalty device active to give a warning upon a change in signal aspect to more restrictive, manually operative means for restoring the device to inactivity, and means, operative only upon the device becoming inoperative, for inflicting a penalty in the form of a trafiic restriction regardless of T actual trafiic conditions' 2. In a train control system, in combination with trackway apparatus for putting train control current on the track rails in accordance with trafiic conditions ahead; car carried apparatus lo including, a receiver, a cab signal having a plurality of aspects of varying restrictivenesses, circuit means controlled by the receiver and controlling the signal, a normally inoperative whistle, operatingmeans for causing the whistle to sound upon a change in signal aspects to less favorable, manually operative means for silencing the whistle, and means, automatically operative only upon the whistle operating means failing, for causing the signal to display its most restrictive indication.

3. In a train control system, in combination with trackway apparatus for putting train control current on the track rails in accordance with trafiic conditions ahead; car carried apparatus including, a receiver, a cab signal having a plurality of aspects of varying restrictivenesses, circuit means controlled by the receiver and controlling the signal, a normally inoperative pneumatically operated whistle, operating means for causing the whistle to sound upon a change in signal aspect to less favorable, manually operative means for silencing the whistle, and means, automatically operative upon the whistle operating means failing, for shunting the receiver and thus causing the signal to display its most restrictive indication.

4. In a train control system, in combination with trackway apparatus for putting train control current on the'track rails in accordance with traffic conditions ahead; car carried apparatus including, a receiver, a cab signal having a plurality of aspects of varying restrictivenesses, circuit means controlled by the receiver and controlling the signal, a source of airunderpressure, awhistle, circuit means operative upon a change of signal aspect to-less favorable to connect the whistle to the source of air to cause the whistle to sound, manual means operable to silence the whistle, and circuit means for causing the signal to display its most restrictive indication and normally maintained inoperative by air pressure from said source.

5. In a train control system, in combination with trackway apparatus for putting train control current on the track rails in accordance with trafiic conditions ahead; car carried apparatus including, a receiver, a cab signal having a plurality of aspects of varyingrestrictivenesses, circuit means controlled by the receiver and controlling the signal, a source of air under pressure, a whistle, circuit means operative upon a change of signal aspect to less favorable to connect the whistle to the source of air to cause the whistle to sound, manual means operable to silence the whistle, a shunt circuit connected across the car carried receiver and including contact means biased to close the shunt circuit, and pneumatically operated means controlled by air from said source for normally maintaining the shunt circuit open.

6. In a train control system, in combination with trackway apparatus for putting train control current on the track rails in accordance with traffic conditions ahead; car carried apparatus including, a receiver, a cab: signal having a plurality of aspects of varying restrictivenesses, circuit means controlled by the receiver and controlling the signal, a source of air under pressure, a Whistle, circuit means operative upon a change of signal aspect to less favorable to connect the whistle to the source'of air to cause the whistle to sound, manual means operable to silence the whistle, a contact in series with the receiver and biased to open the receiver circuit, and pneumatically operated means controlled by air from said source for normally maintaining the receiver circuit closed.

'7. In a train control system, in combination with trackway apparatus for putting train control current on the track rails in accordance with traffic conditions ahead; car carried apparatus including, a receiver, a cab signal having a plurality of aspects of varying restrictivenesses, circuit means controlled by the receiver and controlling the signal, a source of air under pressure, a Whistle, circuit means operative upon a change of signal aspect to less favorable to connect the whistle to the sourceof air to cause the whistle to sound, manual means operable to silence the Whistle, a shunt circuit connected across the car carried receiver and including contact means biased to close the shunt circuit and pneumatically operated means controlled by air from said source for normally maintaining the shunt circuit open, and valve means between said source of air, and the whistle and pneumatically operated means, for silencing the whistle when the 15 car is cut out of service. I

PERCY W. SMITH. 

